Discrete-Time Eye and Scatter Diagrams (Communications Blockset)

Produce an eye diagram and/or scatter diagram

Library

Comm Sinks

Description

The Discrete-Time Eye and Scatter Diagrams block plots eye diagrams and scatter diagrams from a discrete-time complex input signal. The input can be either a scalar or a frame-based column vector.

The Diagram type parameter determines which plots the block produces. The block draws the diagrams in a single window.

The Trace period parameter is the number of seconds represented by the horizontal axis in the eye diagram. The Trace offset parameter is the time value at the left edge of the horizontal axis of the eye diagram. This parameter must be between zero and the Trace period parameter.

Whenever the simulation time modulo the Trace period value equals the Decision point parameter, the block plots a new point in the scatter diagram and a vertical line in the eye diagram. The Decision point parameter must be greater than or equal to the Trace offset parameter, and less than or equal to the sum of Trace period and Trace offset. Furthermore, if the block plots a scatter diagram, then the Decision point parameter must be an integer multiple of the Sample time for plot update parameter.

The two-element Lower and upper bound of incoming signal vector parameter determines the vertical axis in the eye diagram and both axes in the scatter plot.

To specify the plotting color, as well as the line type or marker type, use the Line type parameters that appear after you select a value for the Diagram type parameter. In the Line type for eye diagram parameter, use a slash (/) to separate the specifications for the in-phase and quadrature components of the input signal. Choices for the color, marker, and line types are in the table on the reference page for the Continuous-Time Eye and Scatter Diagrams block.

The Sample time for plot update parameter determines which of the input data the block uses for creating plots. If the parameter matches the sample time of the input signal, then the block uses all available data. If the parameter is an integer multiple of the sample time of the input signal, then the block uses a decimated version of the input data.

Dialog Box

Trace period: The duration of the horizontal axis of the eye diagram, in seconds.
Trace offset: The time at the leftmost edge of the horizontal axis of the eye diagram.
Decision point: The time at which the first point in the scatter plot and the vertical line in the eye diagram are plotted.
Lower and upper bounds of diagram: A two-element vector containing the minimum and maximum signal values in the diagrams.
Number of saved traces: The number of curves in the eye diagram, or points in the scatter plot, that are visible after you resize or restore the figure window.
Diagram type: The diagram(s) that the block produces.
Line type for eye diagram: A string that specifies the color and the line type for the eye diagram. This field appears only when the Diagram type parameter is set to an option that includes an eye diagram.
Line type for scatter diagram: A string that specifies the color and the marker type for the scatter diagram. This field appears only when the Diagram type parameter is set to an option that includes an scatter diagram.
Sample time for plot update: The time interval between successive input values that the block includes in the plot(s).

Limitations

Since this block uses an M-file, you cannot generate C code for it using the Real-Time Workshop.

Discrete Modulo Integrator Discrete-Time VCO